n the period between the two world wars, Italian submarines were developed from three distinct projects: Ansaldo (O.T.O. and C.R.D.A.), Cavallini and Bernardis. While the first was a civilian project, the other two were the results of studies conducted by the Engineering Department of the Navy. The submarines "Fieramosca" and "Pisani" were the first produced from the Bernardis design. They had a simple hull with or without blisters. The "Fieramosca", built by the Tosi shipyard in Taranto in 1926, was initially equipped with a hangar to hold a hydroplane.

Despite various shortcomings of the Bernardis' design, the Regia Marina moved from the experimental phase of the "Fieramosca" to the production, in 1928, of the class "Bandiera", a direct evolution, with a few changes, of the "Pisani" class. During the period 1935-1940, the Regia Marina introduced eight new classes of submarines: amongst them the "Marconi". This class was an evolution of the "Marcello" class which, in its turn, was an evolution of the "Glauco" class. With an increase in displacement of about 10%, the "Marconi" had their range increased by 16% over the "Marcello". During the alterations performed in 1941-42 in Bordeaux, the range of this class was increased even further, but the buoyancy was reduced to dangerously low levels.

As easily noticeable, Italian shipyards, especially in the area of submarine construction paid the consequences of poor planning and lack of standardization. To this point, while the Germans were able to produce similar vessels with mostly exchangeable parts from different shipyards, Italian vessels used parts often peculiar to a specific class, and each class included only a limited number of boats.

The six vessels of the "Marconi" class showed good seaworthiness and easiness of deployment, especially after the reduction in size of the cunning tower. During this alteration work, the periscopes sleeves were lowered, thus reducing the vessel's profile. During its operational life, the "Da Vinci" suffered various breakdowns, serious enough to force the vessel back to port. None of the "Marconi" class submarines survived the war, but surely they were amongst the best vessels produced by Italy, with the "Da Vinci" being the Italian vessels credited with the highest number of sinking (second only to U-boats, and well ahead of Americans, Japanese or British vessels). In Atlantic and Indian Oceans, the six vessels sank a total of 38 ships for a total of 216,227 t., and damaged 17 for a total of 116.686 t.

Of the six vessels, five were lost in Atlantic, while the "Torelli", transformed into a transport submarine, was sized by the Japanese in Singapore upon Italy's surrender. The vessel was transferred from the Japanese to the Germans and renamed U.IT 25, it operated with a mixed German and Italian crew. Upon Germany's surrender, in May 1945, the boat was returned to Japan and named I 504, and it operated with a mix crew, including some Italians.Upon Japan's surrender, the "Torelli" was sank by the American off the Japanese coast near Kobe.

The "Leonardo da Vinci" was built by CRDA of Monfalcone, which also built the "Guglielo Marconi", while the other four vessels - "Maggiore Baracca", Michele Bianchi", "Alessandro Malaspina" and "Luigi Torelli" - were built by O.T.O. of La Spezia.